On Dec 9, 1:26 pm, Grant Erwin wrote:
I have ... two shafts which had gears
fixed to them by pinning.

I'm thinking of temporarily fixing the gear to the shaft somehow, setting
it up in the mill, and drilling

Hand-reaming for a taper pin would be easiest, but if you want to
hold both in a mill, can you make a clamp? Bore a through hole
in scrap for the shaft, widen the hole half-through for the pinion
collar-part, hacksaw a slot, fit the shaft/gear and close the
mill vise on the scrap so as to close the saw kerf and hold
it all still. It sometimes helps to kerf across so the two diameters
are independent (and use a mill vise with some flexibility
in the moving jaw, or put a rocker scrap against that jaw).